Kim Sung Kuk, Lee Jae Kwang, Lee Seoung Ho, Lim Mi S, Lee Soon W, Sim Wonbo, Kim Jong Seung
Department of Chemistry, Institute of Nanosensor and Biotechnology, Dankook University, Seoul 140-714, Korea.
J Org Chem. 2004 Apr 16;69(8):2877-80. doi: 10.1021/jo035567n.
Novel 1,3-alternate calix-thiacalix[4]crown trimers bearing crown-5 and crown-6 were prepared. As proven by X-ray diffraction, in a 1:2 mole ratio of ligand to metal ion, the Cs(+) and K(+) ions prefer to be encapsulated in the trimeric thiacalix[4]crown-6 and crown-5, respectively. On the contrary, the Ag(+) ion was found to be entrapped in the central thiacalix spacer as a 1:1 complex confirmed by (1)H NMR spectrosocpy. Variable-temperature (1)H NMR studies for the trimeric thiacalix[4]crown-6 encapsulating the silver ion revealed that the Ag(+) ion oscillates through the central thiacalix spacer with the aid of cation-pi interactions.
